Dark Matter Candidates

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Dark Matter Candidates
Stefano Scopel
Korea Institute for Advanced Study - Seoul
http//newton.kias.re.kr/scopel
TAUP 2007, Sendai, September 11-15 2007
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Outline

• Evidence for Dark Matter
• Dark Matter properties
• neutrinos
• axions
• WIMP candidates from UED, Little Higgs, SUSY
• The neutralino
• Relic abundance
• Direct detection
• Conclusions
• Topics covered by other talks
• Experimental direct searches (Pierluigi Belli,
  Dan Bauer)
• Indirect detection theory (Lars Bergström)
• Indirect detection experiment (Piergiorgio
  Picozza)

TAUP 2007, Sendai, September 11-15 2007
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Evidence for Dark Matter

• Spiral galaxies
• rotation curves
• Clusters Superclusters
• Weak gravitational lensing
• Strong gravitational lensing
• Galaxy velocities
• X rays
• Large scale structure
• Structure formation
• CMB anisotropy WMAP
• Otot1
• Odark energy0.7
• Omatter 0.27
• Obaryons0.05

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The properties of a good Dark Matter candidate

• stable (protected by a conserved quantum number)
• no charge, no colour (weakly interacting)
• cold, non dissipative
• relic abundance compatible to observation
• motivated by theory (vs. ad hoc)

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The first place to look for a DM candidate
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Neutrino
COLD
HOT

• Smvlt0.66 eV (WMAPLSSSN)
• LEP N?2.9940.012
• ? m?45 GeV
• ? O?h2 10-3
• DM searches exclude 10 GeV
  m? 5 TeV
• (similar constraints for sneutrinos and
  KK-neutrinos)

3 7 GeV
10 eV
mix with sterile component (both for neutrinos
and sneutrinos)
does not work
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beyond the standard model
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(Incomplete) List of DM candidates

• RH neutrinos
• Axions
• Lightest Supersymmetric particle (LSP)
  neutralino, sneutrino, axino
• Lighest Kaluza-Klein Particle (LKP)
• Heavy photon in Little Higgs Models
• Solitons (Q-balls, B-balls)
• Black Hole remnants

TAUP 2007, Sendai, September 11-15 2007
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The axion

• Pseudo Goldstone boson of Peccei-Quinn symmetry
  introduced to explain CP conservation in QCD f
  F ei?

• 3 productions mechanisms in the early Universe
• 1) misalignment (Tgt?QCD) coherent oscillations
  around minimum (Tlt ?QCD)

lt gt if no inflation after PQ phase trans.
average (flat dist.?lt?2gtp2/3)?ma10-5 eV
otherwise smaller ma possible
Tegmark,Aguirre, Rees. Wilczek
(0.3 lt ka lta few)
2) axion strings (TRgtfa) 3) thermal (magt10-3 eV,
subdominant)
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Experimental limits
use data from WIMP searches! (but sensitivity
improves as (MT)1/8)
gagg
a
gagg from theory uncertainty in the masses of
light quarks, (Buckley,Murayama,
arXiv0705.0542) 
g
B
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most popular DM candidates from particle
physics (solve hierarchy problem MW/MPl 10-16)
DM candidate
conserved symmetry

• susy

R-parity
? (neutralino)
K-parity

• extra dimensions

B(1)(KK photon)
T-parity

• little Higgs

BH (heavy photon)
all thermal candidates, massive, with weak-type
interactions (WIMPs)
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the thermal cosmological density of a WIMP X
OXh2 1/ltsannvgtint
x0M/T0
T0present (CMB) temperature
xfM/Tf
Tffreeze-out temperature
Xfgtgt1, X non relativistic at decoupling, low temp
expansion for ltsannvgt ltsannvgtab/x
if sann is given by weak-type interactions ?
OX0.1-1
cohannihilations with other particle(s)
close in mass resonant annihilations
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WIMP direct detection

• Elastic recoil of non relativistic halo WIMPs off
  the nuclei of an underground detector
• Recoil energy of the nucleus in the keV range
• Yearly modulation effect due to the rotation of
  the Earth around the Sun (the relative velocity
  between the halo, usually assumed at rest in the
  Galactic system, and the detector changes during
  the year)

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WIMP differential detection rate
ERnuclear energy NT of nuclear targets vWIMP
velocity in the Earths rest frame

• Astrophysics
• ??WIMP local density
• f(v) WIMP velocity distribution function

• Particle and nuclear physics
• WIMP-nucleus elastic cross
  section

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Different halo models are possible
Interaction on NaI
Belli, Cerulli, Fornengo, Scopel
time-independent part
modulation amplitude
sizeable variation of the local density 0.17 lt ?
lt 1.7
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(No Transcript)
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B(1) relic abundance
Servant,Tait, NPB650,391New J. Phys. 4,99
Kakizai al., PRD71,123522 Kong, Matchev,
JHEP0601,038

• coannihilations (many modes with similar masses)
  
• resonances (MNLKP 2 x MLKP)

• general rule of coannihilation

both cases are possible KK quarks and gluons
vs. KK leptons
OB (1)h20.1
KK leptons
?fractional mass splitting
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• low direct detection signals

?(mq1-mB1)/mB1
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Right-handed KK-neutrino Dark Matter see talk
by M.Yamanaka in parallel session
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GUT unification of gauge couplings
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The neutralino

• The neutralino is defined as the lowest-mass
  linear superposition of bino B, wino W(3) and the
  two higgsino states H10, H20

• neutral, colourless, only weak-type interactions
• stable if R-parity is conserved, thermal relic
• non relativistic at decoupling ? Cold Dark Matter
  (required by CMB data structure formation
  models)
• relic density can be compatible with cosmological
  observations 0.095 O?h2 0.131

?IDEAL CANDIDATE FOR COLD DARK MATTER
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Right-handed sneutrino Dark Matter see talk by
T. Asaka in parallel session
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(No Transcript)
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stau coannihilation
Higgs funnel
SUGRA (a.k.a. CMSSM)
Ellis, Olive, Santoso, Spanos

• only few regions cosmologically allowed
• variants (e.g. non-universality of soft masses at
  the GUT scale or lower unification scale) that
  increase Higgsino content of the neutralino?
  lower relic abundance and higher signals

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Direct detection in SUGRA
Ellis, Olive, Santoso, Spanos
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The Next-to-Minimal MSSM (NMSSM)
solves the µ problem, i.e. why µMEW in µH1H2
superpotential
Higgs soft terms in the NMSSM
NMSSM particle content
The lightest neutralino
CP-even Higgs
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Relic density and direct detection rate in NMSSM
Cerdeño, Hugonie, López-Fogliani, Muñoz,
Teixeira
relic abundance
direct detection
Landau pole
W
?,H lighter ? singlino
H1
Z
H2/2
tachyons
unphysical minima
M1160 GeV, M2320, A?400 GeV, Ak-200 GeV,
µ130 GeV, tan ß5 (sizeable direct detection)

• very light neutral Higgs (mainly singlet)
• light scalars imply more decay channels and
  resonant decays
• neutralino relatively light (lt decay thresholds)
  and mostly singlino
• high direct detection cross sections (even better
  for lower M1)

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Effective MSSM effective model at the EW scale
with a few MSSM parameters which set the most
relevant scales

• M1 U(1) gaugino soft breaking term
• M2 SU(2) gaugino soft breaking term
• µ Higgs mixing mass parameter
• tan ß ratio of two Higgs v.e.v.s
• mA mass of CP odd neutral Higgs boson (the
  extended Higgs sector of MSSM includes also the
  neutral scalars h, H, and the charged scalars H)

• mq soft mass common to all squarks
• ml soft mass common to all sleptons
• A common dimensionless trilinear parameter for
  the third family (Ab At Amq At Aml)
• R M1/M2

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Can the neutralino be ?
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Cosmological lower bound on m?
Bottino, Fornengo, Scopel, PRD68,043506
scatter plot full calculation
upper bound on OCDMh2
curve analytical approximation for minimal
OCDMh2
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Color code ? O?h2 lt 0.095 ? O?h2 gt 0.095
Neutralino nucleon cross section
tight correlation between relic abundance and
?-nucleon cross section
The elastic cross section is bounded from below
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How exp. limit change with different halo models
(CDMS)
largest uncertainty at low masses from high
velocity tail of the the distribution
A. Bottino, F. Donato, N. Fornengo and S. Scopel
Phys.Rev.D72, 083521 (2005)
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Conclusions

• WIMPs at the TeV scale can be realized in
  different well-motivated scenarios (KK photon in
  UED, Heavy photon in Little Higgs, neutralino in
  SUSY)
• Minimal extensions of SM (talk by Tytgat in
  parallel session)
• they can all provide the Cold Dark Matter with
  the correct abundance
• neutralino is still the most popular. Today
  available in different flavours SUGRA, nuSUGRA,
  sub-GUT, Mirage mediation, NMSSM, effMSSM, CPV,
• neutralinos can be light
• astrophysical uncertainties in signal predictions
  
• direct searches are already exploring some SUSY
  scenarios

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Hopefully, soon we will know better
One day, all of these will be LHC phenomenology
papers
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BACK - UP
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Uncertainties in WIMP-nucleon cross section from
nucleonic matrix elements
Bottino,Donato,Fornengo,Scopel, Astrop. Phys.
13,215

• pion-nucleon sigma term
• strange quark content
• almost 1 order of magnitude increase in the most
  extreme case (set 3/set 1)

set 3/set 1
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Littlest Higgs Model with T parity (Birkedal et
al., PRD74, 035002)

• SU(5)/SO(5) global symmetry breaking at f1 TeV
• SM Higgs as Goldstone boson associated with this
  breaking
• Gauged subgroup SU(2)xU(1)2 of SU(5) broken at
  f1 TeV to SM SU(2)LxU(1)Y ? extended gauge
  sector with 4 additional gauge bosons at TeV
  scale WH,WH3, BH, with masses

• T-parity transformation on gauge fields
• SU(2)xU(1)1 ?SU(2)xU(1)2 (SM field even, TeV
  fields odd)
• Heavy photon BH is the lightest T-odd particle
  (LTP) and can play the role of dark matter
  candidate
• BH SM sector weakly coupled ? BH is a WIMP and
  can provide the correct amount of DM as a thermal
  relic

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• Lower bound on scale f from precision electroweak
  constraints f 600 GeV

• Upper bound on scale f from naturalness f 2
  TeV to avoid fine tuning in the Higgs sector

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Direct detection
(a) diagram
(spin independent)
(b)(c) diagrams
(spin dependent)